A known optical connector is disclosed in U.S. Pat. No. 4,167,303 wherein an alignment ferrule of resilient material includes a unitary enlarged collar The resilient ferrule encircles an optical fiber, and is inserted along an alignment sleeve. Radial inward compression of the sleeve on the ferrule radially deforms the resilient ferrule to move the optical fiber to a desired alignment axis within the sleeve. A connector with a resilient ferrule differs from a connector to the field of the invention. A connector according to the field of the invention incorporates a rigid and hard alignment ferrule that relies upon precise dimensions of its external surfaces to align the ferrule within an alignment sleeve.
A known connector according to the field of the invention is disclosed in U.S. Pat. No. 4,634,214 manufactured from metal parts except for a ceramic alignment ferrule that aligns an optical fiber along a straight axial passage of the ferrule. An enlarged collar must be provided on the alignment ferrule. The collar is advantageous. The collar enables assembly of the alignment ferrule with other component parts of the connector. The collar is engaged by a biasing spring to urge the alignment ferrule axially forward into an alignment sleeve.
The alignment ferrule is cylindrical with a straight axial passage. The simple geometry of the ferrule is ideally suited for ceramic material Ceramic material can be molded in simple shapes with small dimensional tolerances. The alignment ferrule of the known connector is manufactured with a metal collar encircling the ceramic alignment ferrule. The collar is secured in place by a frictional force fit or by an adhesive.
A metal collar is readily machined to achieve accurate dimensions and a small size. It has been impracticable to manufacture a ceramic alignment ferrule with an enlarged unitary collar. The collar would add unevenly distributed mass to the alignment ferrule. A small piece part with unevenly distributed mass is difficult to mold in ceramic material, resulting in unacceptable numbers of ill formed piece parts. In addition, ceramic material is extremely hard and resistant to machining.